Air quality, greenhouse gases, and energy policies and procedures

Learn how to comply with air quality, greenhouse gas and energy requirements for your project. To ensure quality analyses, see our standard practices and helpful tools on this page.

Climate adaptation information for projects is available on our Addressing climate change webpage.

Read Environmental Manual Chapter 425: Air quality, greenhouse gases and energy (PDF 312KB) to understand the policy context for project-level analyses.

Analysis decision tree (PDF 526KB) – Refer to this diagram to determine which types of analyses your project requires. If your WSDOT project needs an analysis, inform the Environmental Documentation and Permit Specialist assigned to your project.

Air quality, greenhouse gas and energy guidance (PDF 517KB) - Follow this guidance to ensure your analysis and documentation meet all requirements.

Air quality, greenhouse gas and energy discipline report template (DOCX 1.3MB) – Use this template for project discipline reports. Write one discipline report to cover all air quality, greenhouse gas and energy analyses and documentation that a project requires.

Air quality, greenhouse gas and energy checklist (PDF 125KB) – Refer to this checklist to make sure your documentation meets all requirements.


Projects in air quality maintenance or nonattainment areas must demonstrate conformity. Washington State has areas under maintenance plans for course particulate matter (PM10), fine particulate matter (PM2.5) and carbon monoxide (CO). Find general information about transportation conformity requirements at the Federal Highway Administration's (FHWA) Air Quality and FHWA Transportation Conformity websites.

Carbon monoxide – For projects in CO maintenance areas, use WASIST, the Washington State intersection screening tool. Version 3.0 of the tool uses MOVES2014 (Motor Vehicle Emissions Simulator) emission factors and is approved by the US Environmental Protection Agency's Region 10. To request the tool, contact Jim Laughlin, Puget Sound and Vancouver areas no longer require CO conformity analysis as of October 2016.

Particulate matter – Larger projects in particulate matter maintenance areas may meet the EPA description of a "project of air quality concern" and could require a hot-spot analysis. EPA offers direction on Project-Level Conformity and Hot-Spot Analysis on their website. Refer to Appendix B of EPA’s Transportation conformity Guidance for Quantitative Hot-spot Analysis in PM2.5 and PM10 Nonattainment and Maintenance Areas for descriptions of projects that may and may not require PM hot-spot analysis. If your project may be a project of air quality concern, contact Karin Landsberg,, for assistance with the interagency consultation process.

Fugitive Dust

Reference the Memorandum of Agreement with Puget Sound Clean Air Agency - Fugitive Dust (PDF 22KB) for projects within King, Kitsap, Pierce and Snohomish counties. Refer to the Guide to Handling Fugitive Dust from Construction Projects (PDF 862KB) from the Associated General Contractors of Washington for additional information on fugitive dust best management practices.

Mobile Source Air Toxics (MSAT)

For MSAT analyses, WSDOT follows FHWA's updated interim guidance. If your project includes road segments with more than 140,000 average annual daily traffic, a quantitative MSAT analysis is required.

Refer to the FHWA MSAT Frequently Asked Questions for current information on how to complete an MSAT analysis.

Greenhouse Gas Emissions

Follow the WSDOT Project-Level Greenhouse Gas Evaluations under NEPA and SEPA (PDF 293KB) to address greenhouse gases in project documentation. All WSDOT projects must follow this approach.

Find more information about our approaches to addressing climate change on our Addressing climate change webpage.


Only projects being evaluated at the environmental impact statement (EIS) level require an energy analysis. Follow the Air quality, greenhouse gas and energy guidance and include energy in the same report as air quality and greenhouse gas emissions.

Motor Vehicle Emissions Simulator (MOVES)

For quantitative analysis of operational air quality, greenhouse gas emissions and energy, use EPA's Motor Vehicle Emissions Simulator (MOVES) model. Find more information about the model on EPA’s MOVES webpage. Refer to the Air quality, greenhouse gas and energy guidance for information on state-specific inputs.

14 fish passage projects were completed in 2020

improving access to 54.2 miles of upstream habitat.

11,959 incidents responded to

by WSDOT’s incident Response teams during second quarter of 2021, 15% more than same quarter in 2020.

41 Pre-existing Funds Projects Advertised

during the eighth quarter of the 2019-2021 biennium.